Manufacture of lime and gas.



G. G. FLOYD.

MANUFACTURE OF LIKE AND GAS. nrmonron nun same, 100:. nunwnn nm: a, 1m.

Patented Feb. 1, 1910.

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G. G. FLOYD.

MANUFACTURE OF LIME AND GAS. APPLICATION FILED BEP'LB. '1908. BEIBWED III!!! 3, 1909. 948,045. 7 Patented Feb. 1,1910.

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G. G. FLOYD.

MANUFACTURE OF LIME AND GAS.

APPLICATION FILED SEPT. 8, 190a. RENEWED mm: 3, 190a.

Patented Feb. 1, 1910.

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ture suchas a ove describ UNITED STATES PATENT OFFICE.

GEORGE G. FLOYD, OF KIRKWOOD, MISSOURI.

MANUFACTURE OF LIME AND GAS.

Specification of Letters Patent.

Patented Feb. 1, 1910.

Application filed September 8, 1908, Serial No. 451,959. Renewed June 3, 1909. Serial No. 499,998.

production of quick lime and carbon monoxid (CO) gas from mineral carbonate such as limestone) and or anic substances such as charcoal or coke) t e operation being conducted in retorts, preferably in series and having air 'ti ht connections.

When limestone is bon dioxid (C0,) according to the reaction expressed by the formula (CaCO,-|- heat:

CaO+Co,) and as heated carbon reduces carbon dioxid to carbon monoxid (CO) the e nation for the change bein CO,+C=.= 2%]0 it has been proposed to c ar e into a closed vessel or air tight retortr'a c ose mixture of broken limestone and charcoal or coke, place the retort under asufiicient heat to decompose the mixture, and remove the gas from the retort with an exhauster as 1t is evolved from the decomposing mixture.

As theoretically it takes approximately 12 lbs. of carbon to reduce the carbon dioxid from 100 pounds of limestone to carbon monoxid, it is further proposed that the mixture shall be in such proportions that the carbon in the charcoal will be equal to about ten to twelve per cent., by weight, of the limestone.

When the carbonaceous material is mech'anically mixed with the limestone, ash will be left in the lime and for many puroses this will be .a serious objection, as it owers the grade of the lime. Limestone begins to decompose and evolve CO gas at a temperature materially below the tem-' erature at which lowing carbon will reuce CO gas to C5 gas. Now when itis attempted to roduce CO as from a mixit is necessary to charge such mixture into the retort at a temperature below that required to effect decomposition. In the interval between the decomgosin the O r temperature of limestone and ucing temperature of glowing carbon, gas will be 'evo ved by the decompoeated it evolves car sition of the limestone but will not be reduced, and must either be allowed to escape in the atmosphere and be lost or if allowed to pass to the receiver will dilute the gas therein. Further in converting carbon dioxid gas into carbon monoxid as by the agency of heated charcoal or co e (in accordance with the reaction CO,+C+heat= 2C0) each molecule of the CO gas must come into intimate contact with the heated carbon. Now considering the small available heated area of the charcoal to the unit amount of gas evolved from the limestone in a mixture of the proportions above indiof limestone and carbonaceous material may.

not present such definite relations of the material as to accomplish the desired result.

Again at a certain constant temperature and pressure, CO gas will be evolved from lime-v stone in a relatively constant volume. But as the'process continues the CO gas consumes the carbon and its relative bulk becoming smaller its effective area presented for-the reduction of the CO, gas is correspondingly diminished, and the percentage of CO, gas unreduced will be in an increasing ratio as the decom osition of the limestone proceeds. There ore the gas evolved during the latter stage of the process will contain a larger percentage of CO gas than at the beginning of the process.

. When calcium carbonate 1s heated in a closed vessel it evolves carbon dioxid until a which no further change occurs until the conditions are in some way altered. To

- every temperature there is a corresponding pressure of carbon dioxid which is perfectly definite and constant. When equil rium is reached'at any particular temperature and its corresponding pressure, the calcium carbonate is being decomposed into lime and carbon dioxid at exactly thesame rate as lime and carbon dioxid are re-combining to form calcium carbonate. In order,'therefore, to completely decompose calcium carbonate by heat, it is necessary to keep the pressure of the carbon dioxid as low as possible and the temperature as high as possible. The time and consequently the economy of decomposing limestone in a closed vessel or retort depends, therefore, upon the Work carried on with the CO pressure below or at a temperature above that which would established an equilibrium.

In decomposing a mixture of mineral carbonate and carbonaceous material in a retort closed to the outside air, at a constant temperature, removing the gas as evolved, I found that the time required in so doing was proportional to the CO pressure in the retort. The lower the working CO pressure can be brought below the critical CO pressure that would establish an equilibrium at a temperature which it is practical to maintain, the greater the economy in decomposing the calcium carbonate. To sum up, I found that with a mechanical mixture of mineral carbonates and carbonaceous material it was impossible to reduce entirely all of the CO gas as it was evolved even at the beginning of a fresh charge, and consequently that a certain CO pressure was set up and the speed of decomposing was in proportion to the ratio theCO pressure thus set up bore to the critical pressure corresponding to the temperature of the retort; and as the bulk of the glowing charcoal decreased and the CO pressure increased the time of decomposition slowed up, the ratio of decrease being progressive as the operation continued and the quantity of gas evolved decreasing, of course, correspondingly. The length of time necessary to the working of the process under these conditions renders the operation more expensive and in addition thereto it was found practically impossible to completely calcine the lime rock.

The object of my invention is the rapid and economical production of fuel gas from mineral carbonate, such as limestone, and carbonaceous material such as charcoal or coke, in such manner that a CO gas practically pure and a thoroughly calcined quick lime free from ash or other impurities are obtained. I have discovered that it is possible to accomplish these objects more perfectly by separating the carbonaceous material from the mineral carbonate during the process, and this I may accomplish by superposing the former upon the latter and passing the carbon dioxid through the incandescent mass of carbonaceous material. This may be accomplished by providing a retort with a diaphragm or partition whereby it is divided into two chambers in one of which the mineral carbonates are contained, the other being charged with carbonaceous material, the partition being perforated so that the carbon dioxid gas may pass freely as it is evolved into the glowing mass of carbonaceous material.

My invention in its broader aspects comprises such a disposition of the materials with reference to each other and such a mode of treatment thereof that the CO gas evolved by the decomposition of the limestone will be reduced as formed, thereby avoiding such increased CO pressure as would retard the decomposition of the limestone while by the physical separation of the ingredients the intermixture of the residuum or ash with the quick lime is obviated.

My invention consists, therefore, first in the method of treatment above indicated and hereafter particularly described and claimed, and, second, in certain novel apparatus for carrying out said method.

More specifically stated, my invention consists, first, in the method of reducing gas by the decomposition of a mineral carbonate and passing the gas as evolved therefrom into and through incandescent carbonaceous material of such mass and so arranged as to effect the complete reduction thereof, and the novel apparatus forming a part of my invention consists essentially in a novel construction of the retort whereby the materials may be kept separate and whereby also the carbonaceous material may be kept at practically reducing temperature the ash therefrom being prevented from mixing with the lime, and the sensible heat of the CO gas product being utilized to maintain the carbonaceous material at'a high temperature.

I will now describe a form of apparatus which is well adapted to the carrying out of my improved process, as will be hereinafter pointed out. Said apparatus is shown in the accompanying drawlngs in which Figure 1 is an elevation with parts broken away. Fig. 2 is a vertical sectional elevation on the line 22 of Fig; 1. Figs. 3 and 4 show respectively a longitudinal and a transverse sectional elevation through one of the retorts.

The apparatus shown comprises a series of retorts A, six being a usual number employed in a battery. Each of these retorts is substantially semi-cylindrical in cross section the interior of the retort being further sub-divided into two longitudinal chambers B C by means of a longitudinal curved diaphragm' D provided with a series of minute perforations d. Each of these perforations preferably has an inclination toward the charging end of the apparatus, as clearly inof each retort is closed by suitably shaped,

removabl inserted casting E having two cross-wal s F G, the former being perforated to establish communication between the two chambers B and C...

HY represents a removable cover. which contracted toward its lower end. The upper end of the chamber B has a removable cover plate I --and the upper end of the chamber-t. (i'onmnmicateswith a hopper J. A feed screw K is mounted to operate within said hopper and said feed screwis providedwith a evel gear is which meshes with corresponding gears Z on the drive shaft L. ,These drive shafts as shown in Fig. 1 extend across the battery of retorts tliere being one for each pair and the several drivin shafts areintergeared so that theymay a 1 be driven simultaneously, and

- from asingledriven- Each of the hoppers communicates by a feed pipe M which has a cover N for its upper end and they also Y having anoutlet pipe Q.

I .char ed with lime rock broken to suitable. size andthe chambers C Wlll be charged with i '35 charcoal in the chambers C- and thence up- 7 have communication through pipes 0 provided with asmtable valve wit 1 a header P The chan'1bers B of the retorts will be.

broken or pulverizedcharcoal. this material being fed into the pipes M so as to constitute a store from which the screws K will continuously draw so as to keep these chainbers completely filled. The furnace being charged with fuel: the flame thereofw-illpass upwardly around the retorts and when the proper temperature is attained the decomposition-.of'the limestone will begin. The CO. as evolved therefrom passes through the apertures (1 into and'throug'h the body of ward'ly throughthe hopper, the body of charcoal in the pi es M and through the pipe 0 to the hen or or reservoir P. The

result of this operation is that the limestone is decomposed and the CO ga spasses.

throu h the highly heated carbon and is con ve'rte thereby into CO 'gas and this gas while hot passes through the mass of'ch'arcoal'in the feed pipcsM thus imparting its heat to the charcoal and preliminarily fitting it to be ohargedin the retort, and, at

thesame time, thoroughly filtering the gas through the charcoal mass. The gas inthe. uptake pipes will have a temperature of approximately one-thirdtoone-half the temperature to which the carbonaceous .m'atcrial'must be raised to accomplish the reduction'of the carbondioxid to carbon monoxid. I therefore preferably make the combined uptake andfeed pipes of (-onsideralile'leii'gthj and of such area that the gaswill give .up

practically all of its sensible heat; to.tli('-.-ca i'-' n-aceous. material on; its way to the retort-H and an "economy is thus etl'ected equ'al't'mthe heat units, necessary to b consumed inraising the temperature of the carbonaceous mas,

.terial tothedegrce attained by absorption from the gas. I prefer to connect each of'the retorts independently to the headeror reservoir P and to "provide each with its own supply pipe and it will be noted thatatter the retorts are heatednp there will be maintained continuously amass of heated -car-y.

bonaceous material in the chambers and the ash will be constantly forced int-othelower end of the chamber and can heremoved when 'theretort is opened for the-re 1 moral of the lime. a By means of this novel form-ofapparatus the gas evolved from the limestone of l'lccessity passes through the bed of glowing-carbonaceous material while the ash tronfi'the carbonaceous material is 'l'ire vented from mingling with .the linie which wtmldyno't onlyretard. the operation of producing-gas but would"alsointrod'uce an impurity-into the lime itself.

During this operationj too there is abvays present. such anan ioi'mt of.;"

carbon as to reduce the CO gas asz'evolved,

with the result that all of the C(Lga'sis rednced to CO gas beforeit leavesthe vretoi Wlnle I prefer the form and arrangement of apparatus described. it will be understood I that such apparatus-imiy be varied incon? .struction without departing from the."scope'.

of the invention and thatntlie'several novel features hereindescribed need :not lie-used con' ointly. The general requirement of'snchri.

an apparatus to conform tothe scope ofmy invention is that it shall permit-'oft-he phys'-- ical separation of the carbonaceous material from the limestone, but this-1 night' be*accomplished in a retort of differentZc'onstruc t-ion and arrangement than hereindescribed.

Again, in order to -effecta savm'g'in'the voperation I have shown a--specific @mean s for utilizing the heat of the gas'as'it-leavesthe I retort to preliminarily heatthe carbonaceous material, but the specific. means,by which this is accomplished may be varied.

From the foregoing specificationit wilLbe apparent that the carbon'dloxld gas expands at once into the space filled with the glowing.

carbonaceous material and this materialis of sufficient bulk to atonce'convert or re-.

duce all the CO. gas to (0 gas. the (1mm:

position proceeding at an e-rei'l rate and therewith.

without the formation of silicates ()rfll'llllllnat'es .m. the l'nne or-the mingling of ash It \Vlll further-be observed .that

according to this method the retort'will'b'e hot when a fresh charge of limestone isput in and gas'will begin tobe evolved therefrom when the calcining temperatureisreached. such gas passing immediately into 7 and through the glowing carbonaceous matcrial'wher'eby-it is converted into CO gas and this in 1 turn is passed directlyf into and through the incoming carbonaoebus material which is being constantly fed into the retort, thus effecting the preliminary heating of such carbonaceous material which reaches the retort at such temperature that it will 11p immediately glow. By the method and means above described the operation is practically continuous no' interruption being required vexcept for the removal of the lime and the charging of the 15 limerock and this may be effected without allowing the retort to cool. Furthermore the ash of the carbonaceous material is prevented from mingling with the lime an'dby;

- in the retorts enabling the COgaS to be:

' withdrawn without" drawing-air into the system, thus resulting in purer gas and greater economy.

, '30 Attention is directed to the fact thatan application describing and-claiming the apparatus set out in this application was filed by me' on January :11, '1909,"Seria l ;N0."

471,634. -I claim: r I

1. The herein-described-process of producing fuel gas whichconsists in decomposing a mineral carbonate by heating in an air-tight retort and causing the gas as 4 evolved to pass through an incandescent mass of carbonaceous material, maintained in close proximity to but unmixed with the carbonate, substantially as: described.

' ,2. The hereindescribed process 'of pro- (5 ducing fuelgas which-consists in decomposinga mineral carbonate by heat in anairtight retort evolving thegas directly into a mass of incandescent carbonaceous material, and continuously feeding carbonaceous material into the retort, substantially as described. a v

3; The herein-described process 'of'proq ducing fuel gas which consists in decomposing-a mineral carbonate by heat in an air-' tight retort evolving the gas directly into a 5 mass of. incandescent carbonaceous material, and maintainingthe volume of said carbonaceous material in said retort substantially. constant, substantially as described.

4. The herein-described process of'producing fuel gas'which consists in decomposing a mineral carbonateby heat in an air-- tight retort evolving the gas-directly into a mass of incandescent carbonaceous material, and preliminarily heating abody of car- 61 bonaceous material-by" the heatof said gas after its conversion by said incandescent carbonaceous material, substantially as described.

5. The herein-described process of pro- 7 ducing fuel gas which consists in decomposing a mineral carbonate/by heating in an air-tight retort and causing the gas as evolved to passthrough an incandes nt mass of carbonaceous material maintained 7 inprox-imity to but outof contact with the carbonate. a I 6. The herin-described process of producing fuelgas which consists indecompos ing a mineral carbonate, such-as limestone, 8f

.byfheatf'within a sealed retort or chamber and passing the, gas, as evolved, through an incandescent-mass of carbonaceous material maintained in proximity thereto but out of a contact therewith and then passing the'converted gas through a body of carbonaceous 7 material whereby to preliminarily heat the same,-substantially as described.

7.'The herein-described process of producingfuel gas which consists in charging a mineralcarbonate into a chamber in an airtight retort, continuously feeding a carbonaceous material into a chamber in proximity to and communicating with the chamber containing the mineral carbonate, decomposing the latter by heat to produce CO gas, passing said, gas, as evolved, through an incandescent 7 portion of 'saidcarbonaceous materialwh'ereby to convert the same into CO gas and then pass the CO gas in the 10 heated condition through the iii-coming carbonaceousmaterial whereby to preliminarily heat-the latter, and drawingoff the gas as evolved, substantially as described.

'GEORGE G'LFL'OYD. V Witnesses:

E. B. SHER'ZER, J As. HQ Loom. 

